High Isolation Optical Control Microwave Switch Theory And Technology Research

Optically controlled microwave switch (OCMS) in microwave systems has been investigated in this thesis. The design scheme for the switch by using microwave resonating cells and impanting the photoconductor Si (silicon) is presented. According to the scheme, the switches with high isolation and compact structure have been demonstrated.In Chapter 1, the application background, advantages, the development sketch of OCMS in the worldwide, and the main work of this thesis are introduced. OCMS has been introduced to solve the problem of electromagnetic compatible in reconfigurable antenna and other microwave systems. Comparing with the traditional microwave switch, OCMS has no biasing circuits and electrical controlling signals, so it can not interfere with the performance of microwave systems. In the design of this kind of switch, how to realize the high isolation of it to satisfy the need of system will be considered in this thesis.In Chapter 2, the photoconductivity effect and the reasonable analyze model of it are introduced. In order to apply the complex photoconductivity effect in this project efficiently, the reasonable analyze model of it is presented, and the selection of photoconductor is induced. To insure the insertion loss of the switch at its on state, the effective penetration of the optical induced carrier layer should be equal to the thickness of the Si dice in the model. Then, the working principle of the switch in this thesis is explained.In Chapter 3, the design of microstrip resonator cells are introduced. In order to realize the switch with high isolation, some microstrip resonator cells are presented. Based on the bandstop property of these cells, they can be used in the design of optically controlled microwave switches with high isolation. The simulated and measured results show that there are obvious bandstop character and compact structure of them.In Chapter 4, the design of optically controlled microwave switches with high isolation is presented. The design of these resonating type switches is based on the photoconductivity effect and the property of microstrip resonator cells. In order to make the silicon dice implanted on the resonator cell closely to realize the good metal contact, some enhancements of the dice are induced combining with the content in chapter 2. The measured results of the switch with high isolation have been shown. Then, some phenomena which influence the performances of the switches significantly have been analyzed.In Chapter 5, the summary about the research of the project and the expectation about the future work are presented.